Caffeinated Soul

New to Audi and turbo's, so forgive my ignorance on this.
To start I have read all kinds of posts and search the web for answers on my specific problem and nothing has helped.Its a 2001 Audi S4.

I have no CEL, no limp mode indicator, no shuddering, knocking or anything, the car runs so smooth that you wouldn't think there is a problem. I borrowed one of those Bluetooth obd2 scanners and came back empty handed, but I do have a full log of info if this helps.
I have check all the hoses I can find (havent pressure tested it yet, thats tomorrow.) checked the N75 valve and the waste gate lines, swapped out a few components from another 2.7 such as MAP, and N75. I removed the battery cable and unplugged the MAF sensor and the car started perfect but I got an ABS and ESP light, no CEL.

I used the bluetooth scanner to read my boost levels and found that when I first start the car and start driving the boost is very sporadic, but I dont get on it when its cold. Once it warmed up I gave it some gas and my boost is very low at high rpms like 1-2 psi. Shortly after it will spiked to 19psi at only 2600rpm and then after that it drops off and its almost never goes above -1 to +0 psi.

I looked into my F hose to see if there was a leak there but it looks like there is some kind of F hose delete but there seems to be different kinds of deletes so Im kinda lost as to what the previous owner has down and what should have been done.

Caffeinated Soul

So today I was doing some reading and came across a thread about how to check your PCV. In the thread it mentions to take off oil cap while the car is idol and see if there is a little bit of negative vacuum. Some said the car would start to idol funny and if you didnt have any suction to look into PCV. Today I found I have no negative vacuum on mine and it didnt idol any differently. My N80 will randomly make a fast clicking noise and then stop all of a sudden, possibly a bad N80?

I have a few question about this I would love some help on.

1. How does or does the PCV/N80 affect boost?
2. I cant remember, but I think I read something about then N75 getting vacuum from the manifold?

I started to look for a pattern in my boost levels today when I drove to work and noticed something kinda strange. If I come to a light or a stop sign and then rev through first to about 3500-4k I make about 4psi, but after the first shot of boost I can no longer make positive boost levels. I decided to mess with this a bit and see if this theory held true and took 1st up to about 5-5500 and it said I made 20psi. How is that possible??

What could cause this, and what are some of the things I should look for?

Thanks for the help, it is much appreciated.

kompressorgolf

sounds like other issues, maybe limp mode, scan for engine codes, possibly egt, they dont throw the light on commmonly and put you into limp

make sure its a vag com or vcds as well, some codes wont show up if they are MFG specific

Caffeinated Soul

Well I took my car to my uncles shop since he has a better scanner than the one I use. Turns out both EGT's came up with the same fault "Short to ground - intermittent" I read an article about how the solder points go bad and that they might share a ground so if one needs re soldering, they both go out.
Before I mess that mess I had a question about pressure testing. So I finally got around to testing the system yesterday and as I put pressure on the system I realized it was coming out of the brake boost line the plugs in between the MAF and the Y pipe, I don't remember reading I needed to plug that when testing the system.
Just in case I put my finger over it and gave it pressure, this time I started to get air coming between two parts to the chain tensioner. I included a pic of where it's coming from.

Should that area of the motor even see pressure?

Caffeinated Soul

Update: The last time I was at my uncles shop I had him clear all the codes that came up. After a few days of driving and no change in performance I took the car back to my uncles shop and not a single code exsist. He check everything his scanner could view and the only odd thing was my MAF was reading very slightly about what he said was a normal voltage. It still registered air and spikes when I would hit the gas a bit.

He wasn't able to view anything boost related with his scanner for some reason. I'm running low on ideas to even look for at this point and feel ice hit a wall.
To give you an idea of what's happening I'll try to explain it. Everyone always asks on forums "how does it idle?" Imagine a perfect running s4, no cel, high idle, stuttering, miss fires, smoke from exhaust.

That is exactly what my car is like, I just have very sporadic boost levels. If I stop for a second and then kinda get on it I overboost to 20 psi. However if I'm just rolling in 4th (or any gear) and floor it, the psi hits 0 and flat lines. Then I'll come to a stop again and if I get on it I'll hit 20 psi again. Keep in mind I'm not breaking 4.5k when this happens, if I rev to about 3k I'll get about 6-8psi.

Please help me, I'm don't know where to look anymore.

Caffeinated Soul

Today I found out I have a bad wastegate diaphragm and possibly missing The pin that coactuatore actuator to the wastegste. I figure I could just replace the actuator, and put a new pin on the wastegate, but with 163k on the car and both turbos being leaky I'm just putting new k03's on.
I can't afford to go k04 as of right now, and don't plan on building up the car very much.

Stealership gave me model 078145701sx and 078145702sx for my turbos. My problem is everyone seems to refer to these turbos in a different way suck as k03-052 and such. Are mine part of a different series?